Electrical fuel injection system for internal combustion engines



Oct. 22, 1935. a. WALKER ET AL 5 ELECTRICAL FUEL INJECTION SYS TEM'FORINTERNAL COMBUSTION ENGINES Filed June 20, 1934 INVENTORJ. 75W

. BY 51W @wnsmaL-w ATTORN s.

Patented Oct. 22,1935

UNITED STATES PATENT OFFICE ELECTRICAL FUEL INJECTION SYSTEM FORINTERNAL COMBUSTION ENGINES Application June 26, 1934, Serial No.731,446 29 Claims. (01.123-32) This application is a continuation inpart of our copending application entitled Fuel injection system forDiesel engines, filed September 10, 1930, bearing Serial No. 480,960.

Our invention relates to electrical fuel injection systems for internalcombustion engines of the type wherein the air charge of the combustionchamber is constant regardless of engine speed or throttle position, andwherein the fuel is injected into the combustion chamber in spray form.In internal combustion engines of this type, ignition may be eifected asin the "Diesel cycle, the Otto cycle or by means of the method ofignition fully described and claimed in United States LettersPatent.#l,903,381, issued Aprill l, 1933 to Harry E. Iennedy. We preferthe latter inasmuch as high firing pressures and uncontrolled ignitionlag. are avoided enabling relatively high speeds in engines ofcomparatively light weight per horsepower.

Prior to our invention two methods of injecting fuel into the combustionchamber of internal combustion engines operating on the cycles abovereferred to were in general use. The first method is what is mostcommonly known as the jerk pump system in which an. individual fuel pumpis provided for each cylinder of the engine. The plunger of this pumpacts to create the pressure necessary for injection and at the same timemeters the fuel charge. To throttle the engine, the displacement of thispump is varied. This system has limitations which render it practicallyunsuitable for high speed engine operation, and by high speed we meansspeeds in excess of say approximately 2000 R. P. M. This is manifestwhen it is realized that in this system as the engine speed increases,the hydraulic pressure applied to the injection nozzles increases withgreat rapidity due to the fact that the displace ment stroke of the pumpplunger must take place through a constant crank angle. Therefore, inorder to effect the injection of a constant charge of fuel at allspeeds, the pressure of the fuel at the nozzle or spray valve orificemust vary as the square of the engine speed. Consequently, whencomparatively high engine speeds are appreached, the hydraulic pressureof the'fuel between the pump and the nozzle rises to a point renderingthe system impractical because of mechanical limitations. Further, theplunger of the pump may complete its displacement stroke but due to thecompressibility of the fuel, injection through the nozzle may lagresulting in late burning of the fuel in the combustion charm her andconsequently inemcient engine operation.

It has also been observed that in this system detrimental vibrations areset up in the fuel column between the pump and the spray nozzle by theaction of the pump plunger, which vibrations or pulsatiqnsresult inirregular or erratic injection of each'charge to the detriment of propercombustion and engine operation.

In general, the second well known method of injecting fuel into thecombustion chamber of internal combustion engines operating on the illcycles above set out is commonly termed the common rail system. In thissystem there is a common source of fuel, which is maintained under asubstantially constant pressure, for all of the cylinders of the engine.The injection 15 into the individual cylinders is effected in propertimed relation to the piston strokes through the medium of spray valveswhich are mechanically actuated at properly timed intervals from thecrankshaft of the engine. That is to say, these 20 spray valves are opentmough a predetermined crank angle which may be varied to effectthrottling. Obviously, this angle must be increased as the engine speedsincrease in order that sumcient time will elapse to enable injection ofthe proper fuel charge. There is a limit to which the crank angle can beincreased without causing late burning with consequent inefficientoperation, and it has been found that in using the rail pressure system,this maximum crank angle is insufficient in higher speeds to enableinjection of a proper fuel quantity without the use of excessive fuelpressures. When the maxi mum crank angle and fuel pressure is reached,increasingly smaller 'fuel charges are introduced into the cylinder asthe engine speed is increased, resulting in loss in torque at the higherspeeds.

In both of the above systems, in order to effect the discharge orinjection of a sufficient quantity of fuel at the higher speeds, thesize of orifice in the spray jet must necessarily be so large that whenthe-engine is throttled at reduced load, atomization would becomeso poorthat inefflciept combustion and consequent poor engine operation wouldresult. Another disadvantage which is common to both of the abovesystems of fuel injection is that in the smaller bore engines where thefuel charge is minute, the wear and manufacturing variations of themechanical parts prevents accurate metering with consequent inefficientoperation. This in multiple cylinder engines prevents proper balancebetween the cylinders and ragged uneven engine operation. I

There have been many attempts to employ electromagnetic injection valvesin connection with internal combustion engines. Such valves wereoperated by connecting the windings of the valve to a source ofelectromotive force through the medium of an engine driven contacting,ously known injection mechanism. These types of injection systems lackthe, inherent characteristics essential for proper injection, for thereason that in. order that the current for operating the valve may notreach excessivevalues, the winding of the valve must consist of manyturns of fine wire so "that it will have suflicient resistance to limitthe current to a safe value. The inductance of such a winding is,therefore, correspondingly high and the circuit must have a large timeconstant. The current in such a winding builds up comparatively slowlyso that the maximum value of the magnetic force available does notappear until a comparatively long interval after the closing of thecontact. This at high speed may not reach a value high enough to liftthe valve at all. Assuming, however, that the current reaches a valuesufficient to lift the valve, the reluctance of the magnetic circuitwill have been enormously reduced and in consequence the winding willhave become more highly inductive. When the contacts open, they will berequired to rupture the maximum current with consequent vicious sparkingat the contact points and the development of high eddy current withinthe structure of the valve, tending to retard the closing thereof. Sucha system has inverse characteristics to those which are required. -Itprovides a minimum force when the maximum is necessary at starting anddevelops the maximum force at substantially the moment when it isrequired to close the valve. Furthermore, if the engine stalls with thecontacts closed, the cylinder will be flooded with oil and the batteryrun down. This accounts for the indifferent success of prior attempts toaccomplish electrically what had previously been done mechanically.

It is the principal object of our present invention to provide anelectrical fuel injection system for internal combustion engines whichovercomes all ofthe disadvantages of prior systems and which willoperate efllciently under a moderate constant fuel pressure to inject,during a relatively short angle of the engine crankshaft rotation, anaccurately metered quantity of fuel, regardless of whether the fuelcharges are minute, at properly timed intervals through a speed rangefar exceeding the limits of previsystems.

To accomplish our object we provide anelectrical fuel injection systemwhich includes a common source of fuel maintained under substantiallyconstant pressure. The injection into each cylinder is effected throughthe medium of a magnetic injection valve which is electrically operatedto effect injection at properly timed intervals relative to the pistonoperation. At wide open throttle the injection valve is held open for aconstant time interval regardless of the engine speed and, therefore,regardless of engine speed, a constant quantity of fuel will be injectedinto the cylinder under a constant fuel pressure so that the torque willnot diminish with engine speed, and the injection pressure need not varywith engine speed. At reduced throttle for a. given load, a decrease ofthat load tends to increase the engine speed. This is compensated for bya. corresponding decrease in the fuel charge as the speed increases.Likewise, if

the load increases and the engine speed decreases, the fuel charge isautomatically in creased. Therefore, the system is absolutely andinherently self-governing. To operate the injection valves in thismanner we have provided 5 a source of electromotive force and acondenser which is electrically connected with the source ofelectromotive force and with the magnetic injection valve. The chargeand discharge of this condenser is engine controlled so that thecondenser will act as a. medium by which electrical impulses areperiodically delivered from" the source of electroinotive force to thevalve for operating the latter at properly timed in-' tervals, thecapacity of the condenser, of course, 16 determining the quantity ofeach electrical impulse to the valve.

The invention is exemplified in the following description andillustrated by way of example in the accompanying drawing, in which: 20

Fig. l diagrammatically illustrates one embodiment of our invention.

Fig. 2 diagrammatically illustrates a second embodiment of ourinvention.

Fig. 3 diagrammatically illustrates the application of the distributorto a multi-cylinder engine.

In the present application we disclose two preferred embodiments of ourelectrical fuel injection system' for internal combustion engines. Thesetwo systems are identical in principle and each are equally capable ofproducing ideal fuel injection characteristics which include '(1)constant time duration of injection valve opening 'at wide openthrottle'position regardless of engine speed; and the use of a constantmoderate fuel pressure. This, of course, results in a constantaccurately metered charge of fuel being injected and full torqueproduced at all engine speeds. (2) Inherent self-governing at reduced 40throttle-this is important as it enables the engine to be self-govemingwithout the use of governing auxiliaries on the engine. (3) Accuratelytimed full opening of the injection valve for a controlled exceedinglyshort time duration-this, of course, enables extremely high speeds to bereached in that a full charge of fuel can be injected in an exceedinglyshort period of time which will not exceed the maximum crank anglelimits (even at extremely high speeds) during which fuel must beinjected for proper operation of the engine. Likewise, it enablesproperly timed injection of fuel in high speed engines operating withcomparatively low compression pressures wherein the ignition period mustbe limited to a crank angle comparable with that common to gasolinepractice.

In both of our systems herein disclosed we prefer to employ a magneticinjection valve III which is fully described and claimed in LettersPatent 00 #l,892,956, issued to Harry E. Kennedy January 3, 1933.

In general, this magnetic valve, which is indicated by the numeral it inthe drawing, consists of a housing constituting the stator. cablymounted in this housing is an armature which is connected with a valvemember so that reciprocation of the armature will be accompanied byreciprocation of the valve member. This valve member controls thedischarge of fuel through a nozzle orifice. The fuel is directed to thevalve and the stator is so constructed that the fuel may passtherethrough to gain access to the nozzle when the valve member isunseated.

The magnetic operating structure of the valve Recipro- 06' I is suchthat it has direct force distance characteristics. That is to say, themaximum force exerted on the armature is at the commencement of itsstroke, which force gradually diminishes as it reaches its maximumtravel. In other words, the maximum force to lift the valve from itsseat is exerted at the time injection is to commence, which, of course,results in a very rapid opening of the valve, and conversely permitsequally rapid closing. The closing is effected through the provision ofa spring force or its equivalent exerted against the valve and which isaugmented by the fuel pressure as the valveapproaches its seat. It is tobe noted that this valve operation results in sharp opening and sharpclosing of the nozzle orifice, so necessary to proper engine operation.

The stator of the magnetic structure of the valve is wound so that itwill be of relatively low inductance and consequently its circuit willhave a small time constant This is necessary to effect fuel injectionduring an exceedingly short time duration. It is possible for us toutilize a magnetic valve of relatively low inductance because our valveoperating circuits are capable of delivering current of high intensityto the valve during an extremely short time period, because ourelectrical fuel injection systems are characterized by the inclusion ofa condenser in the valve circuit, the charge and discharge of which isengine controlled. The capacity of this condenser, of course, determinesthe maximum quantity of each electrical impulse delivered to the valvefrom the source of electromotive force provided to supply the necessaryelectrical energy.

In the injection system illustrated in Fig. 1, we have fitted aninjection valve ID, of the type which we have previously described, tothe combustion chamber A of an internal combustion engine B asillustrated. This valve is in constant communication with a source ofliquid fuel which is maintained under a constant moderate pressure in areservoir such as indicated at H. In a multi-cylinder engine this sourceof fuel supply is common to the injection valves of all of thecylinders. i

In the present instance we have preferred to illustrate that typeofengine which operates on comparatively low compression pressures andrequires electrical ignition. For this purpose we have illustrated aspark plug Ila for the purpose of igniting the charge of the combustionchamber preferably by the method of ignition set out in United StatesLetters Patent #1303381, supra.

To provide electrical energy for operating the injection valve ill ofour fuel injection system,

we have provided a source of electromotive force which in this instanceis illustrated as a storage battery l8. We prefer that the voltage ofthis battery be twenty-four volts, although we are aware that othervoltages are equally suitable.

In the injection system illustrated in Fig. 1, there are two circuits; acharging circuit for imposing a charge on a condenser and adischargingcircuit for discharging the quantity of electricity stored inthe condenser to the injection valve for operating the latter. That isto say,

in general, a circuit is completed through the condenser from the sourceof electromotive force to impose a charge thereon. This circuit isopened and the discharging circuit is closed to operate thevalve. It isessential that the discharging circuit be completed at a point in properrelation to the engine crankshaft rotation in order that the injectionwill commence at a defilever l9, the latter having a contact point 20 5adapted to contact with a stationary contact point 2!. This lattercontact point 2| is connected through a conductor 23 to a condenser 24of the uni-directional type having a capacity of approximately 2000micro-farads. The condenser is illustrated as being variable onlybecause it may be desired to vary the condenser capacity for throttlingpurposes. In most instances, however, we prefer that the condensercapacity be fixed inasmuch as we provide a separate medium for varyingthe time constant of the condenser charging circuit for throttlingpurposes. In this instance we have shown a variable resistance 25 asinterposed between the battery 18 and the contact lever IQ for varyingthe time constant of the 0 condenser charging circuit and by this we areenabled, as will be hereinafter described, to effect throttling.

Intermediate the battery It and the variable resistance 25 we interpcsean inductance 26 for 25 the purpose of creating current lag suflicientto enable the contact points and 2| to become firmly seated prior to thecurrent reaching its maximum value. This prevents burning and rapiddeterioration of the contact points.

We desire to point out, however, that we may substitute a variableinductance between the battery l8 and the contact lever IS in lieu ofthe variable resistance and the inductance 26. By means of such avariable inductance we are not only enabled to obtain a throttlingefiect but are also enabled to obtain the current lag necessary to theproper seating of the points 20 and 2| prior to the current reaching itsmaximum value.

It should be pointed out here that it is well known that when acondenser is connected to a source of electromotive force, a momentarycurrent flows until the condenser is charged to a potential equal tothat of the source to which it has been connected. Therefore, when thepoints 20 and 2| contact, current from the battery it flows through theinductance 26, the variable resistance 25, between the contact points 20and H and thence through the conductor 23 to charge the condenser 24.

The timing of the completion and opening of the circuits is such thatsubsequent to the condenser receiving its charge from the battery Hi,the discharging circuit through the valve is completed. By reference tothe drawing, it will be noted that this discharging circuit includes aconductor led from the condenser 24 to a fixed contact point 21 which isadapted to contact with a contact point 28 on a contact lever 29. Thislever in turn is electrically connected through a distributor contactlever 30 to the magnetic injection valve l0. Consequently, when thecondenser discharge circuit is closed by contacting of the points 21 and28, the quantity of electricity stored in the condenser will bedischarged through this discharge circuit through the valve in a timeinterval predicated upon the inductance and the capacity of thedischarge circuit. It is necessary, however, that this circuit be closedat a definite angle of crankshaft rotation and be maintained closed asufficient time duration to enable full discharging of the condenser tothe valve.

It will be noticed that in order to operate the contact levers l9 and 29in properly timed relation that we have provided a cam 22 which isengine operated and so formed and timed that the contact arms will bealternately operated and the contacts 21 and 2! closed at a definiteangle of crankshaft rotation. We may prefer to advance and retard thebeginning of fuel injection, when it is found necessary under certainoperating conditions where the engine is to be operated through a widespeed range. This may beeasily accomplished and we have done so inpractice by fitting an automatic governor to the cam 22 in the samemanner that the automatic governor is fitted to the cam which operatesthe breaker arm in the ignition systems of conventional automotivedesign. In connection with the distributor contact arm 30, it'may besaid that this is merely illustrated and described in this applicationin order to illustrate the application of our injection system tomultiple cylinder engines as in Fig. 3. It maybe pointed out, however,that the points operated by the distributor arm 30 contact prior to thecontacting of the points 21 and 28 of the discharge circuit and suchcontact endures untilafter the opening of the contact points 21 and 28.This is in order that no current will be broken by the points of thedistributor contact lever.

It should also be pointed out that the inductance of the winding of themagnetic structure of the valve Ill serves the same purpose in thedischarging circuit in preventing sparking at the contact points 21. and28 as does the fixed inductance 26 in thecharging circuit in preventingsparking" at the contact points 20 and.

It is obvious that in reality the condenser in the circuit functions asa current transformer because it is possible to draw a relatively smallcurrent during the comparatively long charging period that the chargingcircuit is closed, and then to subsequently discharge into the valve acurrent whose maximum value may exceed many times the charging currentdrawn from the battery.- This is important because at the instant ofinjection valve opening, a great force is necessary to rapidly overcomethe inertia of moving parts and the unbalanced fuel oil pressure andthereby provide a sharp valve opening. Likewise, by the use of thecondenser, the opening force falls rapidly to zero to obtain a sharpclosing of 'the injection valve. 7

Such a condition is inherent in the circuit which we have just describedbecause the instant that the discharging circuit closes, full condenserpotential accelerates the current rapidly to its maximum value andconsequently maximum force is developed in the magnetic operatingstructure of the valve nearly simultaneously with the closing of thecircuit. The rapid lowering of potential across the condenser due to thedepletion of its charge permits the current to die away quickly. Aslight reversal may occur, due to the tendency of such a circuit tooscillate, which demagnetizes the valve and tends to prevent sticking oftheparts thereof.

We have determined in practice by means of an oscillograph and astroboscope that the first increment of fuel just emerges from the sprayvalve tip when the current reaches its crest value and that injectioncontinues until the current has gone slightly negative and that we caninject a full charge of fuel through the injection valve illustrated inan injection period of of a second. As previously pointed out, it isexceedingly important that short injection duration be attained,particularly in engines in the higher speed range or in the lowercompression engines in which ignition is effected by means 5 ofelectrical ignition, such as disclosed in United States Letters Patent#1,903,381, supra.

It maybe here emphasized that the duration of the contact time in thedischarging circuit has nothing whatever to do with the time todischarge 10 the condenser through the valve circuit, but that thecontact duration on the charging circuit does determine the quantity ofelectricity that will be stored on the plates of the condenser. Thisgives rise to engine characteristics which are desirable. Thischaracteristic of our circuit enables the engine to becomeself-governing. That is to say, a reduction of engine speed due toincreased load results in a greater quantity of electricity stored inthe condenser and the subsego quent discharge into the injection valvewill be correspondingly greater with an equivalent increase of fuel sothat as the speed decreases, there is a continuous increase in thequantity of fuel injected per cycle until the maximum quantity 2; whichthe engine is capable of burning is injected.

It is also apparent that if the engine-speed increases due to a decreasein load that a lesser quantity of electricity will be stored in the con-30 denser and that the subsequent discharge into the injection valvewill be correspondingly lesser with an equivalent decrease of fuel sothat as the speed increases, there will be a continuous decrease in thequantity'of fuel injected per cycle. 5

To throttle the engine, of course, the time constant of the condensercharging circuit is varied by means of the variable resistance 25. Thethrottling eifect of varying the time constant of the condenser chargingcircuit is, of course, ap- 4 parent.

There is another inherent advantageous characteristic of our iniectionsystem. That is, when the throttle is at idling position, with theresistance of the condenser charging circuit at its maxi- 45 mum, andthe engine is over driven, the magnitude of the electrical impulsedelivered to the magnetic structure of the injection valve will beinsufllcient to lift the valve and consequently no fuel will be injectedinto the combustion cham- 5o ber. The advantage of this is apparent, forexample,'when the engine is used as a brake in a vehicle whiledescending grades, at which time the engine will, of course, beoperating at a speed greater than idling but with the throttle set at 65idling position. The duration of time which the condenser. chargingcircuit is closed will, therefore, be materially shortened so that thequantity of electricity discharged to the injection valve will beinsufficient to lift the valve member 60 thereof from its seat.Therefore, the engine can be freely used as a brake without anylikelihood of crank case dilution or loading up in the combustionchamber. I

In Fig. 2 we have illustrated a fuel injection as system for internalcombustion engines which has all the advantageouscharacteristics of thesystem illustrated-in Fig. 1 and previously described .herein. Thesystem is composed of the'same elements, the difference being in theelectrical cir- 70 cults connecting these elements. Reference being hadto Fig. 2, it will be seen that this system also: includes a magneticinjection valve 50 of the type previously described which is suppliedwith fuel oil under a constant pressure from a reservoir 5| hi ly is Theelectrical operating system for this valve 50 includes two circuits,which we prefer to term a charging circuit and a discharging circuit.That is to say, a circuit is completed through a condenser and the valve58 in the charging circuit and then a discharging circuit is completedwhich fully or partially discharges the condenser as will be more fullydescribed. It is essential, of course,

- that the charging circuit be completed at a point in proper relationto the engine crankshaft rotation in order that the. injection willcommence at a definite point with relation to the engine crankshaftrotation.

What we have termed here the charging circuit includes a battery 52which is electrically connected with a condenser 53 of the same type asused in the system illustrated in Fig. 1. This condenser is connected bymeans of a conductor 54 to a stationary contact point 55 which isadapted to contact with a contact point 58 on a contact lever 51. Thecontact lever 51 is electrically connected to the injection valve 50through a distributor 58. This distributor 58 is illustrated anddescribed in order to illustrate the application of our injection systemto multiple cylinder engines. It should be pointed out here also thatthe contact points of the distributor 58 contact prior to the contactingof the points 55 and 5B and such contact endures until after the openingof the points 55 and 56 in order that no current will be broken by thepoints of the distributor contact arm 58.

It will, therefore, be seen that at the moment that the charging circuitis closed due to the contacting of the points 55 and 5B, theelectromotive force "of the battery causes a momentary rush of currentthrough the condenser 53 to the valve 50, operating the latter. Thiscurrent, which during its existence operates the valve, is quicklybrought to zero by the building up of a countervoltage in the condenserwhich opposes the electromotive force of the battery 52. Obviously, theelectrical charge which the condenser 53 can receive determines themagnitude of the impulse delivered to the valve 58 and consequentlydetermines the time duration of injection.

After the valve has been operated by what we term the charging circuit,the condenser 53 is discharged through the discharge circuit. For thispurpose the condenser 53 is connected by a conductor 59 to a contactpoint which is adapted to contact with a point 6| on a contact lever 52,the latter being connected back to the-condenser through a variableresistance 63 and an inductance 64. When the contact points 80 and GIcontact, the condenser 53 is, of course, discharged. The value of theresistance of the circuit and the time of duration of the contactbetween the points 60 and BI, of course, will determine the degree towhich the condenser will have been discharged. Consequently, the degreeto which the condenser has been discharged in turn determines thequantity of electricity re quired in the succeeding closing of thecharging circuit to fully charge the condenser. It is this amount thatdetermines the magnitude of the impulse delivered to the valve 58 sothat by varying the time constant of the discharging through the mediumof the variable resistance 83 we are enabled to effect throttling of theengine by changing the time duration of opening of the injection valve58.

The inductance 54 is in the'discharging circuit, of course, to create acurrent lag to enable the contact points 65 and SI to become firmlyseated circuit prior to the building up of the current to its maximumvalue.

It will be noticed that we employ a cam 85 which is engine operated tooperate the contact levers 51 and 62 in properly timed relation. This 5cam is so formed and timed that the contact arms will be alternatelyoperated and the contacts 55 and 58 will be closed at a definite angleof crankshaft rotation. In practice, we have fitted this cam 65 with anautomatic governor 10 to advance and retard the beginning of fuelinjection but it is not believed necessary to illustrate this featurebecause the automatic governor operates the cam 65 to accomplish advanceand retard in the same manner as the 15 automatic governor which isfitted. to the cam which operates the breaker arm in ignition systems ofconventional design.

It will be seen that the difference in the injection system shown inFig. 1 and that shown 20 in Fig. 2 is that in the system shown in Fig. 1the operation of the injection valve is the result of a current flowwhich discharges the condenser, while in the system shown in Fig. 2 theoperation of the fuel valve is the result of a current flow 25 whichcharges the condenser. The two systems, however, have the common featurethat the condenser is always in the injection valve circuit and that thequantity of energy stored in the condenser in both systems is determinedby 30 changing the time constant of a circuit in which the condenser isinterposed. That is to say, in the fuel injection system shown in Fig.1, the degree to which the condenser is charged is relied upon forthrottling purposes, which regulation is attained by varying the timeconstant of the charging circuit of the condenser. In the system shownin Fig. 2, the degree to which the condenser is discharged is variedwhich is attained by varying the time constant of the dis- 0 chargingcircuit of the systemby means of a variable resistance included in thecircuit.

As previously pointed out, however, both systems here disclosed producethe same advantageous engine operating characteristics and have the sameinherent advantageous characteristics. That is to say, both systemsgwilloperate emciently with the use of a constant moderate fuel pressure toinject, during a relatively short angle of the crankshaft rotation anaccurately 5o metered quantity of fuel regardless of whether the fuelcharges are minute and that injection will commence at an accurate givenpoint relative to crankshaft rotation. Further, the time of duration ofvalve opening is exceedingly short. and accurate in order that a properfuel charge can be injected in engines in the higher speed range and inlow compression engines utilizing electrical ignition wherein the fuelcharge must be injected during a relatively short angle of thecrankshaft rotation.

While we have shown two preferred methods of practicing our invention,it is to be understood that various changes may be made therein by thoseskilled in the art without departing from the invention as defined inthe appended claims.

Having thus described our invention, what we claim and desire to secureby Letters Patent is:

andclosingsaidcircmtsalternatelyandinsynchronism with the enginecrankshaft operation.

2. A fuel injection system for internal combustion engines whichincludes a magnetic fuel injection valve, a source of electromotiveforce, a variable condenser, a charging circuit connecting the source ofelectromotive force with the condenser, a circuit connecting thecondenser with the valve, engine operated means opening and closing saidcircuits alternately and in synchronism with the engine crankshaftoperation.

3. A fuel injection system for internal combustion engines whichincludes a magnetic fuel injection valve of low inductance, a battery, acondenser, an electrical charging circuit electrically connecting thebattery with the condenser, an electrical discharging circuitelectrically connecting the condenser with said valve, means operated bythe engine in timed relation with the engine crankshaft to alternatelyopen and close said circuits whereby to charge the condenser from saidbattery and discharge the condenser to said valve to operate the latter.

4. Afuel injection system for internal combustion engines whichincludesa magnetic fuel injection valve, 8. source of electromotive force, acondenser, a charging circuit connecting the source of electromotiveforce with the condenser, a discharging circuit connecting the condenserwith the valve, engine operated means opening and closing said circuitsalternately and in synchronism with the engine crankshaft operation, anda variable resistance interposed in said charging circuit to vary thetime constant thereof.

5. A fuel injection system for internal combustion engines whichincludes a magnetic fuel injection valve of low inductance, a battery, acondenser, an electrical charging circuit electrically connecting thebattery with the condenser, an electrical discharging circuitelectrically connecting the condenser with said valve, means operated bythe engine in timed relation with the engine crankshaft to alternatelyopen and close said circuits whereby to charge the condenser from saidbattery and discharge the condenser to said valve to operate the latter,and a variable resistance interposed in said charging circuit to varythe time constant thereof.

6. A fuel injection system for internal combustion engines whichincludes amagnetic fuel injection valve, a source of electromotiveforce, an operating circuit connecting the source of electromotive forcewith said valve for operating the latter, engine operated means forperiodically closing said circuit, a condenser in said circuit todetermine the quantity of the electrical impume'delivered from thesource of electromotive force to the valve each time said circuit isclosed, a discharge circuit associated with the condenser fordischarging the same during the period said operating circuit is open,an engine operated means opening and closing said circuit.

7. A fuel injection system for internal combustion engines whichincludes a magnetically operated fuel iniection valve, a source ofelectromotive force. an electrical connection between said source ofelectromotive force and said valve for operating the latter, engineoperated means for rendering said electrical connection between theelectromotive force and the valve periodically effective, a condenser insaid connection determiningthequantityoftheelectrical chargedeliveiedfrom the source of electromotive force to the valve during eacheil'ectiveperiod of said connection, and engine operated means effectingthe discharge of the condenser during the ineifective periods of saidconnection.

8. A fuel injection system for internal combustion engines whichincludes a magnetic fuel injection valve, a source of electromotiveforce, an electrical connection between said source of electromotiveforce and said valve for operating the latter, engine operated means forrendering said electrical connection between the elec- 10 tromotiveforce and the valve periodically ef-, fective, a condenser in saidconnection determining the quantity of each electrical charge deliveredfrom the source of electromotive force to the valve during eacheffective period of said con- 15 nection, a discharge circuit to eiIectthe discharge of the condenser during the ineil'ective periods of saidconnection, engine operated means operating in timed relation to theengine to open and close said circuit, a variable resistance in saidcirgo cult to vary the time constant thereof.

9. A fuel injection system for internal combustion engines whichincludes a magnetic fuel injection valve, a source of electromotiveforce. an operating circuit connecting the source of elecg5 tromotiveforce with said valve for operating the latter, engine operated meansfor periodically closing said circuit, a condenser in said circuit todetermine the magnitude of the electrical impulse delivered from thesource of electromotive so force to the valve each time said circuit isclosed,

a discharge circuit associated with the condenser for discharging thesame during the period said operating circuit is open, engine operatedmeans operating in timed relation to the engine as for opening andclosing said discharge circuit, and a variable resistance in saiddischarge circuit to vary the time constant thereof.

10. A fuel injection system for internal combustion engines whichincludes a magnetic fuel 40 injection valve, a source of electromotiveforce, an electrical connection between said source of electromotiveforce and said valve for operating the latter, engine operated means forrendering said electrical connection between the electromotive force andthe valve periodically effective, a condenser in said connection todetermine the magnitude of the electrical impulse delivered from thesource of electromotive force to the valve during each effective periodof said connection, a discharge circuit to effect the discharge of thecondenser during the ineifective periods of said connection,engineoperated means operating in timed relation to the engine to openand close said discharge circuit, and an inductance in said dischargecircuit.

11. A fuel injection system for internal combustion engines whichincludes a magnetic fuel injection valve, a source of electromotiveforce, an operating circuit connecting the source of electromotive forcewith said valve for operating the latter, engine operated means forperiodically closing said circuit, a condenser in said circuit todetermine the quantity of the electrical harge delivered from the sourceof clectromotive force to the valve each time said circuit is closed, adischarge circuit associated with the condenser for discharging the sameduring the period said operating circuit is open, engine operated meansoperating in timed relation to the m gine for closing the bustionengines which cal charge delivered bustion engines which includes amagnetic fuel injection valve, a source ofelectromotive force, anoperating circuit connecting the source of electromotive force with saidvalve for operating the latter, engine operated means for periodicallyclosing said circuit, a condenser in said circuit to determine thequantity of the electrical charge delivered from the source ofelectromotive force to the valve each time said circuit ,is closed, adischarge circuit associated with the condenser for discharging the sameduring the period said operating circuit is open, engine operated meansoperating in timed relation to the engine for opening and closing thedischarge circuit, and an inductance in said discharge circuit.

' 3. A fuel injection system for internal combustion engines whichincludes a magnetic fuel injection valve, a source of electromotiveforce, an electrical connection between said source of electromotiveforce and said valve for operating the latter, engine operated means forrendering said electrical connection between the electromotive force andthe valve periodically effective, a variable'condenser in saidconnection to determine the magnitude of the electrical impulsedelivered from the source of electromotive force to the valve duringeach effective period of said connection, a discharge circuit efiectingthe discharge of the condenser during the ineffective periods of saidconnection, and an engine operated means operating in timed relation tothe endischarge circuit during the ineffective periods of saidconnection.

14. A fuel injection system for internal comincludes a magnetic fuelinjection valve, a source of electromotive force, an operating circuitconnecting the source of electromotive force with said valve foroperating the latter, engine operated means for periodically closingsaid circuit, a variable condenser in said circuit to determine thequantity of the electrical charge delivered from the source ofelectromotive force to the valve each time said circuit is closed, adischarge circuit associated with the condenser for discharging the sameduring the period said operating circuit is open, engine operated meansfor opening and closing the discharge circuit, and an inductance in saiddischarge circuit.

15. A fuel injection system for internal com bustion engines whichincludes a magnetic fuel injection valve, a source of electromotiveforce, an operating circuitconnecting the source of electromotive forcewith said valve for operating the latter, engine operated means forperiodically closing said circuit, a variable condenser in said circuitto determine the quantity of the electrifrom the source of electromotiveforce to the valve each time said circuit is closed, a discharge circuitassociated with the condenser for discharging the same during the periodsaid operating circuit is open, engine operated means for closing thedischarge circuit, and a variable resistance in said discharge circuit.

16. A fuel injection system for internal combustion engines whichincludes a source of liquid fuel under a constant pressure, a source ofelectromotive force, a condenser, a charging circuit connecting thesource of electromotive force with the condenser, a discharging circuitconnecting the condenser with the valve, engine operated means openingand closing said circuits alternately, said means closing thedischarging circuit injection valve in constant engine operated means atan exact point relative to the engine crankshaft rotation.

1'7. A fuel injection system for internal combustion engines whichincludes a source of liquid fuel under a constant pressure, a magneticfuel communication with said source of fuel, a source of electromotiveforce, an electrical vconnection between said source of electromotiveforce and said valve for operating the latter, engine operated means forrendering said electrical connection between the electro: motive forceand the valve periodically effective, a condenser in said electricalconnection determining the magnitude of the electrical impulse deliveredfrom the source of electromotive force to the valve during eacheffective period of said connection, and engine operated means effectingthe discharge of the condenser during the ineffective periods of saidconnection.

18. A fuel injection system for internal combustion engines whichincludes a source of electromotive force, a condenser, anelectromagnetic fuel injection valve, two electrical circuits eachassociated with said condenser, the electromotive force being connectedto one of said circuits, the valve being connected to one of saidcircuits, for opening and closing said circuits to cause a current toperiodically flow in said circuits alternately and in synchronism withthe engine operation to alternately charge and discharge said condenser,the current flow from the condenser in one of said circuits beingutilized to operate said valve.

19. A fuel injection system for internal combustion engines whichincludes a source of electromotive force, a condenser, anelectromagnetic fuel injection valve, ciated with said condenser, theelectromotive force forming a part of one of said circuits, the valveforming a part of one of said circuits, said circuits being so arrangedthat when said circuits are alternately rendered effective a currentorigi nating in the electromotive force will flow through one circuitand charge the condenser and then flow through the other circuit todischarge the condenser, the electromotive force, the condenser andvalve being so associated with said circuits that the flow of thecurrent from the condenser for alternately rendering said circuitseffective in synchronism with the operation of the crankshaft of theengine.

20. A fuel injection system for internal combustion engines whichincludes a source of electromotive force, a condenser, anelectromagnetic fuel injection valve, two electrical circuits of whichsaid condenser forms a part, the electromotive force forming a part ofone circuit, the valve forming a part of one circuit, said circuitsbeing so arranged that when said circuits are alternately renderedeffective a current originating in the electromotive force will flowthrough one circuit and charge the condenser and then flow through theother circuit to discharge the condenser, the electromotive force, thecondenser and valve being so associated with said circuits that the flowof the current from the condenser in one of said circuits will flowthrough the valve to operate the same, a medium in one of said circuitsfor varying the resistance thereof to vary the magnitude of thedisplacement current flowing through said valve, and engine operatedswitch means for alternately rendering said circuits effective, saidmeans operating in syn-.

two electrical circuits asso.--

- bustion engines which includes chronism with the operation of thecrankshaft o! the engine.

21. A fuel injection system for internal combustion engines whichincludes a source of electromotive force, a condenser, anelectromagnetic fuel injection .valve, a charging circuit and adischarging circuit electrically associated with said condenser, theelectromotive force being associated with said charging circuit, saidcondenser and electromotive force being so associated with said circuitsthat a current originating in the electromotive: force will flow in thecharging circuit to charge the condenser when the charging circuit isrendered effective, the condenser being so associated with thedischarging circuit that when the latter is efiective it will dischargethe condenser, the said valve being so disposed in one of said circuitsthat the displacement current flow in said circuit from the condenserwill energize the electromagnetic valve and operate the same, andengineoperated switch means in said circuits for alternately renderingsaid circuits eilective and ineilective in timed relation and insynchronism with the engine operation.

22. A fuel injection system for internal combustion engines whichincludes a source of elec-.- tromotive force, a condenser, anelectromagnetic fuel injection valve, a charging circuit and adischarging circuit electrically associated with said condenser, theelectromotive force and condenser being associated with the chargingcircuit whereby when the charging circuit is rendered effec tive acurrent originating in the electromotive force will flow in the chargingcircuit to charge the condenser, the condenser being so associated withthe discharging circuit that when the discharging circuit is renderedeifective it will discharge the condenser, the valve being disposed inone of said circuits so that the current flow in said circuit from thecondenser will energize the electromagnetic valve and operate the same,means for varying the resistance of one of said circuits whereby to yarythe magnitude of the current flow to the valve, and engine operatedmeans in said circuits for alternately rendering the same effective andinefifective in timed relation and in synchronism with the engineoperation.

23. A fuel injection system for internal combustion engines whichincludes a source of electromotive force, a condenser, anelectromagnetic fuel injection valve, a charging circuit and adischarging circuit electrically associated with said condenser, theelectromotive force forming a part of the charging circuit so that whenthe charging circuit is rendered effective a current originating in theelectromotive force will iiow in the charging circuit to charge thecondenser, the condenser being so associated with the dischargingcircuit that when the latter is rendered eifective it will discharge thecondenser, the valve being so disposed in one of said circuits that thecurrent flow in said circuit from the condenser will energize theelectromagnetic valve and operate the same, means for varying theresistance of the circuit other than the last-mentioned circuit to varythe magnitude of the current to the valve, and engine operated means insaid circuits for alternately rendering the same eilective andineffective in alternate relation and in synchronism with the engineoperation.

24. A fuel injection system for internal coma normally open chargingcircuit and a normally open discharging circuit. a battery, a condenser,said battery and condenser being included in the charging circuit,

I the condenser being included in the discharging circuit, engineoperated means for alternately rendering said circuits effective and insynchronism with the engine operation whereby the cur- 5 chargingcircuit and a normally open discharging circuit, a battery, a variablecondenser, said bat tery and condenser being included in the chargingcircuit, the condenser being included in the discharging circuit, engineoperated means for alternately rendering said circuits effective and 20in synchronism with engine operation whereby the current flow in thecharging circuit will charge the condenser and the current flow in thedischarging circuit will discharge the condenser, an electromagneticfuel injection valve included in 25 one of said circuits in a mannerwhereby current flow in said circuit from the condenser will operate thevalve.

26. A fuel injection system for internal combustion engines whichincludes a normally open 30 charging circuit and a normally opendischarging circuit, a battery, a condenser, said battery and condenserbeing included in the charging circuit, the condenser being included inthe discharging circuit, engine operated means for alternately 35rendering said circuits eiiective and in synchronism with the engineoperation whereby the current flow in the charging circuit will chargethe condenser and the current flow in the discharging circuit willdischarge the condenser, an electro- 40 magnetic fuel injection valveincluded in one of said circuits in a manner whereby current flow in.said circuit from the condenser will operate the valve, and means forvarying the resistance of the circuit other than the one in which thevalve 5 is included to vary the magnitude of the current flow to thevalve.

27. A fuel injection system for internal combustion engines whichincludes a source of electromotive force, a condenser, anelectromagnetic 0 fuel injection valve, a charging circuit includingsaid source of electromotive force and said condenser, a dischargingcircuit including the condenser, engine operated means for opening andclosing said circuits alternately and in synchronism with the engineoperation to cause a current to periodically and alternately flow insaid circuits in synchronism with the engine operation and therebyalternately charge and discharge said condenser, the saidelectromagnetic valve be- 60 ing included in one of said circuits and sodisposed therein that the current flow from the condenser in saidcircuit will actuate said valve, and an electrical medium associatedwith the other circuit to vary the magnitude of the displacement 05current flo""ng to the valve.

28. A Iuel injection system for internal combustion engines whichincludes a source of electromotive force, a condenser, anelectromagnetic fuel injection valve, a normally open charging cir- 70cuit, a normally open discharging circuit, the said charging circuitincluding the electromotive force and the valve, a condenser in saidcircuit between the electromotive force and the valve whereby thecondenser will limit the magnitude of the current 75 flow to the valvewhen said circuit is rendered eflective, the discharging circuitincluding the condenser for discharging the same when said circuit isrendered effective, and engine operated 5 means for alternatelyrendering said circuits eijective in timed relation and in synchronismwith the engine operation.

29; A fuel injection system for internal combustion engines whichincludes a source of electromotive force, a condenser, anelectromagnetic fuel injection valve, a normally open charging circuit,a normally open discharging circuit, the said charging circuit includingthe electromotive cluding the condenser for discharging the same whensaid circuit is rendered effective, engine operated means foralternately rendering said circuits effective in timed relation and insynchronism with the engine operation, and a variable 10 resistance insaid discharging circuit.

: BROOKS WALKER.

HARRY E. KENNEDY.

